"Underwater set (color changing)": Virtual Booster

No more rares or mythics	Primordial Carnivor    U  Creature – Crocodile Whenever Primordial Carnivor attacks, choose a color. Primordial Carnivor must be blocked by a creature of that color this turn if able. As long as Primordial Carnivor is untapped, it has hexproof. 5/4	"Reclusive Tentativer"    U  Creature – Merfolk : Target permanent becomes the color of your choice until end of turn. Whenever you Paint, add one mana of any color to your mana pool. (You paint whenever you change or add a color to a spell or permanent.) 2/2	No more uncommons	No more commons
No more commons	No more commons	No more commons	Drop of Blood    C  Instant Attacking creature gets +2/+0 until end of turn. Raise the red tide. (Until end of turn, all spells and permanents are red and all lands are Mountains in addition to their other types.)	No more commons
Singe    C  Instant Singe deals 1 damage to target creature. That creature becomes black until end of turn. Burnt flesh. Blackened soul.	Deepsea Merfolk    C  Creature – Skeleton Merfolk Aversion from nonblack (This creature can't be blocked or targeted by anything that is not black.) Deepsea Merfolk can’t block. 1/1	No more commons	"Radiant Virus"    C  Instant Choose a color. Creatures of the chosen color get -1/-1 until end of turn.	No more commons

Primordial Carnivor (uncommon)
"Reclusive Tentativer" (uncommon)
Drop of Blood (common)
Singe (common)
Deepsea Merfolk (common)
"Radiant Virus" (common)